3,239 research outputs found
What has been the tax competition experience of the past 20 years?
This paper describes tax reforms in OECD countries over the last 20 years and how they are related to tax competition. Both individual countries? reforms and multilateralinitiatives and developments are covered. This is followed by an overview of theempirical evidence on tax competition. Our conclusion is that the evidence for someinterdependence in tax setting behaviour is strong, although the exact process driving thisremains unclear. While the most basic tax competition models fail to explain thedevelopment in OECD countries, there is more than one possible explanation for thereforms undertaken if more advanced models are considered. The multilateral initiativesthat were implemented however do not seem to be related to resource-based taxcompetition, instead they are about taxing rights. This paper describes tax reforms in OECD countries over the last 20 years and how they are related to tax competition. Both individual countries? reforms and multilateralinitiatives and developments are covered. This is followed by an overview of theempirical evidence on tax competition. Our conclusion is that the evidence for someinterdependence in tax setting behaviour is strong, although the exact process driving thisremains unclear. While the most basic tax competition models fail to explain thedevelopment in OECD countries, there is more than one possible explanation for thereforms undertaken if more advanced models are considered. The multilateral initiativesthat were implemented however do not seem to be related to resource-based taxcompetition, instead they are about taxing rights
Issues in the design and implentation of an R&D tax credit for the UK
R&D tax credits have become a popular policy tool for encouraging research and development (R&D) spending by business, with many countries offering subsidies of this form. The divergence between private and social rates of return to R&D expenditure by private firms provides one of the main justifications for government subsidies to R&D.2 In order to achieve the optimal level of R&D investment, government policy aims to bring private incentives in line with the social rate of return. An R&D tax credit does this by reducing the cost to the firm of doing R&D. Recent empirical evidence suggests that R&D tax credits are an effective instrument in stimulating additional R&D. However, in order to be desirable, a policy needs to be cost-effective and implementable.
This Briefing Note reviews some of the major issues in the design and implementation of R&D tax credits. In Section 2, we briefly discuss the existing tax treatment of R&D in the UK. In particular, we outline the new Research and Development Allowance - which is an allowance for expenditure on plant, machinery and buildings for use in scientific research and which is available to firms of all sizes - and the tax credit for R&D that is available to small and medium-sized enterprises (SMEs). We then discuss, in Section 3, some of the main design features of tax credits that have been implemented in other countries. The discussion mainly concerns the question of how to target new or incremental R&D so as to keep down the total exchequer cost. We discuss problems that arise in defining incremental R&D and how these can be tackled. In Section 4, we provide estimates of the amount of new R&D and the exchequer cost that would be likely to result from implementing different designs of R&D tax credit in the UK. Section 5 concludes. Some technical details are dealt with in the Appendix
How has the UK corporation tax raised so much revenue?
We analyse a puzzle in the UK corporation tax: by both historic and international standards corporation tax revenues have been high while the statutory rate has been low. Possible explanations include the following: changes in tax law that may have increased effective tax rates; other factors such as higher profitability or different macro-economic conditions may have led to higher effective tax rates; and finally the size of the corporate sector may have increased. We find evidence for all three explanations, although none would be sufficient in itself. To the extent that higher profits, particularly financial sector profits may have led to high revenues, there are doubts as to whether revenues will continue to be so strong
Theory of Coherent -Axis Josephson Tunneling between Layered Superconductors
We calculate exactly the Josephson current for -axis coherent tunneling
between two layered superconductors, each with internal coherent tight-binding
intra- and interlayer quasiparticle dispersions. Our results also apply when
one or both of the superconductors is a bulk material, and include the usually
neglected effects of surface states. For weak tunneling, our results reduce to
our previous results derived using the tunneling Hamiltonian. Our results are
also correct for strong tunneling. However, the -axis tunneling results of
Tanaka and Kashiwaya are shown to be incorrect in any limit. In addition, we
consider the -axis coherent critical current between two identical layered
superconductors twisted an angle about the -axis with respect to
each other. Regardless of the order parameter symmetry, our coherent tunneling
results using a tight-binding intralayer quasiparticle dispersion are
inconsistent with the recent -axis twist bicrystal
BiSrCaCuO twist junction experiments of Li {\it et
al.}Comment: 11 pages, 13 figures, submitted to Physical Review
Holomorphic Anomaly in Gauge Theories and Matrix Models
We use the holomorphic anomaly equation to solve the gravitational
corrections to Seiberg-Witten theory and a two-cut matrix model, which is
related by the Dijkgraaf-Vafa conjecture to the topological B-model on a local
Calabi-Yau manifold. In both cases we construct propagators that give a
recursive solution in the genus modulo a holomorphic ambiguity. In the case of
Seiberg-Witten theory the gravitational corrections can be expressed in closed
form as quasimodular functions of Gamma(2). In the matrix model we fix the
holomorphic ambiguity up to genus two. The latter result establishes the
Dijkgraaf-Vafa conjecture at that genus and yields a new method for solving the
matrix model at fixed genus in closed form in terms of generalized
hypergeometric functions.Comment: 34 pages, 2 eps figures, expansion at the monopole point corrected
and interpreted, and references adde
Single-ion and exchange anisotropy effects and multiferroic behavior in high-symmetry tetramer single molecule magnets
We study single-ion and exchange anisotropy effects in equal-spin
tetramer single molecule magnets exhibiting , , ,
, , or ionic point group symmetry. We first write the
group-invariant quadratic single-ion and symmetric anisotropic exchange
Hamiltonians in the appropriate local coordinates. We then rewrite these local
Hamiltonians in the molecular or laboratory representation, along with the
Dzyaloshinskii-Moriay (DM) and isotropic Heisenberg, biquadratic, and
three-center quartic Hamiltonians. Using our exact, compact forms for the
single-ion spin matrix elements, we evaluate the eigenstate energies
analytically to first order in the microscopic anisotropy interactions,
corresponding to the strong exchange limit, and provide tables of simple
formulas for the energies of the lowest four eigenstate manifolds of
ferromagnetic (FM) and anitiferromagnetic (AFM) tetramers with arbitrary .
For AFM tetramers, we illustrate the first-order level-crossing inductions for
, and obtain a preliminary estimate of the microscopic
parameters in a Ni from a fit to magnetization data.
Accurate analytic expressions for the thermodynamics, electron paramagnetic
resonance absorption and inelastic neutron scattering cross-section are given,
allowing for a determination of three of the microscopic anisotropy
interactions from the second excited state manifold of FM tetramers. We also
predict that tetramers with symmetries and should exhibit both
DM interactions and multiferroic states, and illustrate our predictions for
.Comment: 30 pages, 14 figures, submitted to Phys. Rev.
Epidemic threshold in structured scale-free networks
We analyze the spreading of viruses in scale-free networks with high
clustering and degree correlations, as found in the Internet graph. For the
Suscetible-Infected-Susceptible model of epidemics the prevalence undergoes a
phase transition at a finite threshold of the transmission probability.
Comparing with the absence of a finite threshold in networks with purely random
wiring, our result suggests that high clustering and degree correlations
protect scale-free networks against the spreading of viruses. We introduce and
verify a quantitative description of the epidemic threshold based on the
connectivity of the neighborhoods of the hubs.Comment: 4 pages, 4 figure
Time Correlation Functions of Three Classical Heisenberg Spins on an Isosceles Triangle and on a Chain: Strong Effects of Broken Symmetry
At arbitrary temperature , we solve for the dynamics of single molecule
magnets composed of three classical Heisenberg spins either on a chain with two
equal exchange constants , or on an isosceles triangle with a third,
different exchange constant . As T\rightrarrow\infty, the Fourier
transforms and long-time asymptotic behaviors of the two-spin time correlation
functions are evaluated exactly. The lack of translational symmetry on a chain
or an isosceles triangle yields time correlation functions that differ
strikingly from those on an equilateral trinagle with . At low ,
the Fourier transforms of the two autocorrelation functions with
show one and four modes, respectively. For a semi-infinite range, one
mode is a central peak. At the origin of this range, this mode has a novel
scaling form.Comment: 9 pages, 14 figures, accepted for publication in Phys. Rev.
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