The experimental precision achievable in modern experiments on ep-scattering 
allows for measuring the cross section and spin asymmetries in Bethe-Heitler 
(BH) and semi-inclusive deep inelastic scattering (SIDIS) processes with 
unprecedented accuracies. The QED radiative correction is one serious source 
of systematical uncertainties and therefore must be known with any 
predetermined accuracy. Several available calculations provide only leading 
logarithm accuracy (for BH), performed only for unpolarized target (for SIDIS),
 and/or have certain other limitations. In this report we present the results 
of exact calculation of RC for BH process for unpolarized target as well as 
for both longitudinally and transversely polarized targets. Details of the 
calculations of the three key components such as i) the calculation of the 
cross section of two-photon-emission process and analytic integration over 
additional kinematical variables, ii) extraction of infrared divergence using 
the dimensional regularization, and iii) calculation of loop effects with 
extraction and complete cancellation of the infrared divergence, are discussed.
 Also we present an approach for exact calculation of RC in semi-inclusive 
process. The general task of exactly calculated RC in semi-inclusive processes 
for arbitrary target polarization requires the calculation of the covariant 
SIDIS hadronic tensor, important intermediate quantity. Recent results for its 
calculation are presented and discussed.